This invention relates to apparatus for the fitness and sports training of wheelchair users, and more particularly to four-wheel everyday and sports wheelchair support apparatus for permitting more effective workouts.
Wheelchairs are commonly used by physically disabled persons both for everyday transportation and for participating in sports activities such as basketball, tennis and road racing. The typical "everyday" wheelchair includes a frame to which two large rear wheels are rotatably mounted for being hand-driven by the user, one on each side of the frame for supporting the frame along with two small front pivotable wheels or casters, an example of which is shown in U.S. Pat. No. 4,966,362 to Ramaekers. The typical sports wheelchairs--also with two large drive wheels and two small front caster wheels--are generally stronger and more maneuverable than an everyday wheelchair; an example of such a sports wheelchair is shown in U.S. Pat. No. 4,500,102 to Haury et al. Another type of wheelchair, known as a "racer" wheelchair and used for competition racing, has three wheels--two large rear drive wheels and a single non-caster front wheel somewhat smaller than the rear wheels, such as shown in U.S. Pat. No. 5,333,894 to Mayes. Each of the afore-mentioned U.S. Patents are incorporated herein by herein by reference.
Physiological training of the wheelchair user, whether for rehabilitation, fitness, or proficiency in one or more sports, has been implemented in the past by various exerciser or trainer devices. In one such exerciser, disclosed in Ramekers U.S. Pat. No. 4,966,362, a pair of rollers are rotatably mounted in a frame with their rotational axes parallel to each other and spaced to cradle the wheelchair's drive wheels. The wheelchair is backwardly driven up a ramp and the rear wheels are rolled into the roller cradle with the front caster wheels resting on the ramp. The wheelchair user drives the drive wheels of the stationary wheelchair, and the drive wheels drive the rollers in which the wheels are cradled.
It has been experienced that the contact of the rubber tires at the periphery of the wheelchair's drive wheels, when drivably cradled between the two rollers, produces undesired drag, "scrubbing" the rubber from the tires while often providing an audible squeal. Such undesired drag imparts increased resistance to drive wheel rotation, to the extent that a user with little hand strength may be unable to effectively drive the drive wheels when engaged with the rollers. These phenomena are thought to be caused by the circumstance that the wheelchair's drive wheels are generally set closer together at the top than at the bottom, a condition referred to as "camber". Scrubbing may be further increased if the rear drive wheels are additionally set so that they are closer together at the front than at the back (or closer together at the back than at the front), a condition known as "toe".
Trainers for three-wheel racer wheelchairs are known where scrubbing is substantially reduced. One such trainer includes a single roller for being driven by the racer wheelchair's two drive wheels, with the front wheel supported in place such that the center of each of the drive wheels are directly vertically above the roller rotational axis. Another such prior art trainer, developed by the present inventors, utilizes two rollers of different diameters with their rotational axes parallel to one another and with the crest of each roller in the same horizontal plane. When used with a racer wheelchair, the wheelchair is positioned such that its front wheel is supported in place such that the centers of its drive wheels are directly vertically above one or the other of the roller axes for driving the roller which is contacted by the drive wheels. When used with a four-wheel everyday wheelchair or sports wheelchair, however, the wheelchair's drive wheels are cradled between the two rollers with the front caster wheels resting on the ramp. The compact configuration of four-wheel everyday and sports wheelchairs has, in the past, precluded the realization of trainer apparatus for supporting such wheelchairs with the centers of their drive wheels directly vertically above the longitudinal axis of one roller for driving that roller.